Also found in: Dictionary, Acronyms, Wikipedia.
(the name “malm” is given by English stonemasons to soft clayey oolite limestones), in geology, the uppermost division of the Jurassic system. The term was proposed by the German geologist A. Oppel in 1856-58. The Malm is subdivided into four stages: Callovian, Oxfordian, Kimmeridgian, and Upper Volgian (the last is called the Portlandian or Tithonian in different countries). A number of West European geologists classify the Callovian in the Middle Jurassic. The accumulation of marine deposits in the Malm was associated with a vast transgression. Limestone and flysch strata are especially typical of the Malm. In the USSR it is extensively developed on the Eastern European Platform, in Western Siberia, the Caucasus, the Crimea, and the Pamirs.